On the one-year anniversary of his presidency, Barack Obama and the Democratic leadership in Congress have received a stinging verdict on their collaborative reign. By electing Republican Scott Brown over Democratic state Attorney General Martha Coakley to succeed in the late Ted Kennedy’s Senate seat, the voters of a state that Obama carried by 26 points in 2008 have sent a clear message that the legislative excesses of the majority party are too much for even the residents of the reliably liberal Bay State to bear.

Brown’s stunning five-point upset victory has already inspired its share of intraparty recrimination, much of it justified. It seems clear, for instance, that Coakley ran an inept and ultimately uninspired campaign, one that took victory for grantedand paid the price for its complacency. One could also argue, as some Democratic insiders have, that the party’s campaign committee failed to foresee the dangers of Brown’s insurgent populist candidacy, intervening to save Coakley’s faltering campaign only after it was too late. Whatever the merit of these post-mortems, they also miss the broader lessons of Brown’s seismic triumph.

Domestic criminal trials for terrorists are a losing issue for Democrats. Brown scored some of his greatest successes when he assailed Coakley for her stand on national security. Some of Coakley’s wounds were self-inflicted, as when she insisted, against all evidence to the contrary, that there were no terrorists active in Afghanistan. But Brown was also able to tap into the mainstream view, which runs counter to the Obama administration’s policy, that terrorist detainees should not be entitled to criminal protections. In the aftermath of the Christmas terror plot, when aspiring underwear bomber Umar Farouk Abdulmutallab kept mum after being granted an attorney, there is little public appetite for terrorists with possible knowledge of new plots to be afforded the right to remain silent. Extending these civil liberties to terrorists is not only a national security threat. Brown’s victory suggests that it also a political danger to Democrats.

Even Democratic-leaning states oppose the Democrats’ health care overhaul. In its final poll before the election, the well-regarded Democratic polling firm Public Policy Polling found that the Massachusetts’ electorate was deeply skeptical of the Democrats’ health care plan, with 48 percent of voters opposing the plan. Considering that the state’s 2006 health care law was seen as an early model for the national reform, Brown’s win is the latest indictment of the Democrats’ vision of an expanded government role in health care. Because Coakley was a supporter of health care reform, Brown was able to capitalize on popular skepticism by running as the self-styled “41st vote” who could stop the health care bill. He will now have the chance to make good on that promise.

Independents are disenchanted with the Democratic leadership. While Massachusetts is often seen as a liberal bastion, more than half the electorate is made up of independents. Their support proved critical to Brown’s victory. Even as liberal Boston voted the party line, independent voters from the state’s suburbs turned the tide in Brown’s favor. That follows a pattern in other battleground states, including Virginia and New Jersey, where an independent-led insurgency helped down Democratic incumbents. Against this backlash from independents, President Obama’s influence was ineffectual. Despite a last-minute stumping effort on Coakley’s behalf, Obama did little to help her cause. With his approval rating slipping below 50 percent, yesterday’s redeemer of Democratic Party fortunes has become today’s bystander in defeat.

The anti-Democratic revolt has crossed party lines. Although Democratic spinmeisters and partisans worked overtime to cast Brown as the tool of hateful right-wing interests and tea-party reactionaries – MSNBC loudmouth Keith Olbermann scraped bottom with an unhinged and invective-laden rant assailing Brown as an “irresponsible, homophobic, racist, reactionary, ex-nude-model, tea-bagging supporter of violence against women and against politicians with whom he disagrees” – the discomfiting truth for the party is that Brown’s appeal blurred party lines. Some polls had Brown drawing support from nearly 20 percent of registered Democrats. That Democrats can no longer count on the loyalties of party faithful even in staunchly “blue” states is a poignant commentary on both the failures of Congressional Democratic leadership and a reflection of the growing populist backlash against Democrats’ misrule.

If Brown’s victory represents a severe judgment on the failings of the Democrats’ leadership, it’s not clear that they have gotten the message. One might think that Democrats would be chastened by the Massachusetts results. But the only lesson that Democrats seem to have learned from the race is that they need to be even more arrogant in pursuing an unpopular legislative agenda. When, in the final days of the race, it looked like Brown could indeed win, Democrats floated the idea of ramming the health bill through backchannels – whether by bypassing the Senate altogether and sending the House-approved version straight to President Obama or else by resorting to the “nuclear” option that would allow them to pass the bill with a 51-vote majority. Both options are widely considered political suicide, but such is the Democrats’ commitment to the legislation that even the prospect of certain defeat may be a weak deterrent.

Democrats’ missteps are of course only part of the story of the Massachusetts race. The other is Scott Brown. Savvy, charismatic and clued into voters’ concerns, Brown’s campaign was everything that Coakley’s was not. Both the Coakley campaign and President Obama poked fun at Brown’s regular-guy image – particularly the well-worn GMC truck with which he traversed the state. But it’s Brown who will have the last laugh. In one of his final campaign stops, Brown promised to pack up his “truck and drive it straight to Washington.” Thanks to the Democrats’ blunders and to his political skills, he’s on his way.